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Genesis-Plus-GX/core/io_ctrl.c

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/***************************************************************************************
* Genesis Plus
* I/O controller (Genesis & Master System modes)
*
* Support for Master System (315-5216, 315-5237 & 315-5297), Game Gear & Mega Drive I/O chips
*
* Copyright (C) 1998-2003 Charles Mac Donald (original code)
* Copyright (C) 2007-2019 Eke-Eke (Genesis Plus GX)
*
* Redistribution and use of this code or any derivative works are permitted
* provided that the following conditions are met:
*
* - Redistributions may not be sold, nor may they be used in a commercial
* product or activity.
*
* - Redistributions that are modified from the original source must include the
* complete source code, including the source code for all components used by a
* binary built from the modified sources. However, as a special exception, the
* source code distributed need not include anything that is normally distributed
* (in either source or binary form) with the major components (compiler, kernel,
* and so on) of the operating system on which the executable runs, unless that
* component itself accompanies the executable.
*
* - Redistributions must reproduce the above copyright notice, this list of
* conditions and the following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************************/
#include "shared.h"
#include "gamepad.h"
#include "lightgun.h"
#include "mouse.h"
#include "activator.h"
#include "xe_1ap.h"
#include "teamplayer.h"
#include "paddle.h"
#include "sportspad.h"
#include "graphic_board.h"
uint8 io_reg[0x10];
uint8 region_code = REGION_USA;
static struct port_t
{
void (*data_w)(unsigned char data, unsigned char mask);
unsigned char (*data_r)(void);
} port[3];
static void dummy_write(unsigned char data, unsigned char mask)
{
}
static unsigned char dummy_read(void)
{
return 0x7F;
}
/*****************************************************************************
* I/O chip initialization *
* *
*****************************************************************************/
void io_init(void)
{
/* Initialize connected peripherals */
input_init();
/* Initialize IO Ports handlers & connected peripherals */
switch (input.system[0])
{
case SYSTEM_GAMEPAD:
{
port[0].data_w = (input.dev[0] == DEVICE_PAD2B) ? dummy_write : gamepad_1_write;
port[0].data_r = gamepad_1_read;
break;
}
case SYSTEM_MOUSE:
{
port[0].data_w = mouse_write;
port[0].data_r = mouse_read;
break;
}
case SYSTEM_ACTIVATOR:
{
port[0].data_w = activator_1_write;
port[0].data_r = activator_1_read;
break;
}
case SYSTEM_XE_1AP:
{
port[0].data_w = xe_1ap_1_write;
port[0].data_r = xe_1ap_1_read;
break;
}
case SYSTEM_WAYPLAY:
{
port[0].data_w = wayplay_1_write;
port[0].data_r = wayplay_1_read;
break;
}
case SYSTEM_TEAMPLAYER:
{
port[0].data_w = teamplayer_1_write;
port[0].data_r = teamplayer_1_read;
break;
}
case SYSTEM_MASTERTAP:
{
port[0].data_w = mastertap_1_write;
port[0].data_r = mastertap_1_read;
break;
}
case SYSTEM_LIGHTPHASER:
{
port[0].data_w = dummy_write;
port[0].data_r = phaser_1_read;
break;
}
case SYSTEM_PADDLE:
{
port[0].data_w = paddle_1_write;
port[0].data_r = paddle_1_read;
break;
}
case SYSTEM_SPORTSPAD:
{
port[0].data_w = sportspad_1_write;
port[0].data_r = sportspad_1_read;
break;
}
case SYSTEM_GRAPHIC_BOARD:
{
port[0].data_w = graphic_board_write;
port[0].data_r = graphic_board_read;
break;
}
default:
{
port[0].data_w = dummy_write;
port[0].data_r = dummy_read;
break;
}
}
switch (input.system[1])
{
case SYSTEM_GAMEPAD:
{
port[1].data_w = (input.dev[4] == DEVICE_PAD2B) ? dummy_write : gamepad_2_write;
port[1].data_r = gamepad_2_read;
break;
}
case SYSTEM_MOUSE:
{
port[1].data_w = mouse_write;
port[1].data_r = mouse_read;
break;
}
case SYSTEM_XE_1AP:
{
port[1].data_w = xe_1ap_2_write;
port[1].data_r = xe_1ap_2_read;
break;
}
case SYSTEM_ACTIVATOR:
{
port[1].data_w = activator_2_write;
port[1].data_r = activator_2_read;
break;
}
case SYSTEM_MENACER:
{
port[1].data_w = dummy_write;
port[1].data_r = menacer_read;
break;
}
case SYSTEM_JUSTIFIER:
{
port[1].data_w = justifier_write;
port[1].data_r = justifier_read;
break;
}
case SYSTEM_WAYPLAY:
{
port[1].data_w = wayplay_2_write;
port[1].data_r = wayplay_2_read;
break;
}
case SYSTEM_TEAMPLAYER:
{
port[1].data_w = teamplayer_2_write;
port[1].data_r = teamplayer_2_read;
break;
}
case SYSTEM_MASTERTAP:
{
port[1].data_w = mastertap_2_write;
port[1].data_r = mastertap_2_read;
break;
}
case SYSTEM_LIGHTPHASER:
{
port[1].data_w = dummy_write;
port[1].data_r = phaser_2_read;
break;
}
case SYSTEM_PADDLE:
{
port[1].data_w = paddle_2_write;
port[1].data_r = paddle_2_read;
break;
}
case SYSTEM_SPORTSPAD:
{
port[1].data_w = sportspad_2_write;
port[1].data_r = sportspad_2_read;
break;
}
case SYSTEM_GRAPHIC_BOARD:
{
port[1].data_w = graphic_board_write;
port[1].data_r = graphic_board_read;
break;
}
default:
{
port[1].data_w = dummy_write;
port[1].data_r = dummy_read;
break;
}
}
/* External Port (unconnected) */
port[2].data_w = dummy_write;
port[2].data_r = dummy_read;
}
void io_reset(void)
{
/* Reset I/O registers */
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
io_reg[0x00] = region_code | (config.bios & 1);
io_reg[0x01] = 0x00;
io_reg[0x02] = 0x00;
io_reg[0x03] = 0x00;
io_reg[0x04] = 0x00;
io_reg[0x05] = 0x00;
io_reg[0x06] = 0x00;
io_reg[0x07] = 0xFF;
io_reg[0x08] = 0x00;
io_reg[0x09] = 0x00;
io_reg[0x0A] = 0xFF;
io_reg[0x0B] = 0x00;
io_reg[0x0C] = 0x00;
io_reg[0x0D] = 0xFB;
io_reg[0x0E] = 0x00;
io_reg[0x0F] = 0x00;
/* CD unit detection */
if (system_hw != SYSTEM_MCD)
{
io_reg[0x00] |= 0x20;
}
}
else
{
/* Game Gear specific registers */
io_reg[0x00] = 0x80 | (region_code >> 1);
io_reg[0x01] = 0x00;
io_reg[0x02] = 0xFF;
io_reg[0x03] = 0x00;
io_reg[0x04] = 0xFF;
io_reg[0x05] = 0x00;
io_reg[0x06] = 0xFF;
/* initial !RESET input */
io_reg[0x0D] = IO_RESET_HI;
/* default !CONT input */
if (system_hw != SYSTEM_PBC)
{
io_reg[0x0D] |= IO_CONT1_HI;
}
/* Memory Control register (Master System and Game Gear hardware only) */
if ((system_hw & SYSTEM_SMS) || (system_hw & SYSTEM_GG))
{
/* RAM, I/O and either BIOS or Cartridge ROM are enabled */
io_reg[0x0E] = (z80_readmap[0] == cart.rom + 0x400000) ? 0xE0 : 0xA8;
}
else
{
/* default value (no Memory Control register) */
io_reg[0x0E] = 0x00;
}
/* I/O control register (Master System, Mega Drive and Game Gear hardware only) */
if (system_hw >= SYSTEM_SMS)
{
/* on power-on, TR and TH are configured as inputs */
io_reg[0x0F] = 0xFF;
}
else
{
/* on SG-1000 & Mark-III, TR is always an input and TH is not connected (always return 1) */
io_reg[0x0F] = 0xF5;
}
}
/* Reset connected peripherals */
input_reset();
}
/*****************************************************************************
* I/O ports access from 68k (Genesis mode) *
* *
*****************************************************************************/
void io_68k_write(unsigned int offset, unsigned int data)
{
switch (offset)
{
case 0x01: /* Port A Data */
case 0x02: /* Port B Data */
case 0x03: /* Port C Data */
{
/*
D7 : Unused. This bit will return any value written to it
D6 : TH pin output level (1=high, 0=low)
D5 : TR pin output level (1=high, 0=low)
D4 : TL pin output level (1=high, 0=low)
D3 : D3 pin output level (1=high, 0=low)
D2 : D2 pin output level (1=high, 0=low)
D1 : D1 pin output level (1=high, 0=low)
D0 : D0 pin output level (1=high, 0=low)
*/
io_reg[offset] = data;
port[offset-1].data_w(data, io_reg[offset + 3]);
return;
}
case 0x04: /* Port A Ctrl */
case 0x05: /* Port B Ctrl */
case 0x06: /* Port C Ctrl */
{
/*
D7 : /HL output control (1=TH input level, 0=forced high)
D6 : TH pin is 1=output, 0=input
D5 : TR pin is 1=output, 0=input
D4 : TL pin is 1=output, 0=input
D3 : D3 pin is 1=output, 0=input
D2 : D2 pin is 1=output, 0=input
D1 : D1 pin is 1=output, 0=input
D0 : D0 pin is 1=output, 0=input
*/
if (data != io_reg[offset])
{
io_reg[offset] = data;
port[offset-4].data_w(io_reg[offset-3], data);
}
return;
}
case 0x07: /* Port A TxData */
case 0x0A: /* Port B TxData */
case 0x0D: /* Port C TxData */
{
io_reg[offset] = data;
return;
}
case 0x09: /* Port A S-Ctrl */
case 0x0C: /* Port B S-Ctrl */
case 0x0F: /* Port C S-Ctrl */
{
/*
D7-D6 : Serial baud rate (00= 4800 bps, 01= 2400 bps, 10= 1200 bps, 11= 300 bps)
D5 : TR pin functions as 1= serial input pin, 0= normal
D4 : TL pin functions as 1= serial output pin, 0= normal
D3 : 1= Make I/O chip strobe /HL low when a byte has been received, 0= Do nothing
D2 : read-only (on read, 1= Error receiving current byte, 0= No error)
D1 : read-only (on read, 1= Rxd buffer is ready to read, 0= Rxd buffer isn't ready)
D0 : read-only (on read, 1= Txd buffer is full, 0= Can write to Txd buffer)
*/
io_reg[offset] = data & 0xF8;
return;
}
default: /* Read-only ports */
{
return;
}
}
}
unsigned int io_68k_read(unsigned int offset)
{
switch(offset)
{
case 0x01: /* Port A Data */
case 0x02: /* Port B Data */
case 0x03: /* Port C Data */
{
/*
D7 : Unused. This bit will return any value written to it
D6 : TH pin input level (1=high, 0=low)
D5 : TR pin input level (1=high, 0=low)
D4 : TL pin input level (1=high, 0=low)
D3 : D3 pin input level (1=high, 0=low)
D2 : D2 pin input level (1=high, 0=low)
D1 : D1 pin input level (1=high, 0=low)
D0 : D0 pin input level (1=high, 0=low)
*/
unsigned int mask = 0x80 | io_reg[offset + 3];
unsigned int data = port[offset-1].data_r();
return (io_reg[offset] & mask) | (data & ~mask);
}
default: /* return register value */
{
return io_reg[offset];
}
}
}
/*****************************************************************************
* I/O ports access from Z80 *
* *
*****************************************************************************/
void io_z80_write(unsigned int offset, unsigned int data, unsigned int cycles)
{
/* I/O Control register */
if (offset)
{
/*
Bit Function
--------------
D7 : Port B TH pin output level (1=high, 0=low)
D6 : Port B TR pin output level (1=high, 0=low)
D5 : Port A TH pin output level (1=high, 0=low)
D4 : Port A TR pin output level (1=high, 0=low)
D3 : Port B TH pin direction (1=input, 0=output)
D2 : Port B TR pin direction (1=input, 0=output)
D1 : Port A TH pin direction (1=input, 0=output)
D0 : Port A TR pin direction (1=input, 0=output)
*/
/* Send TR/TH state to connected peripherals */
port[0].data_w((data << 1) & 0x60, (~data << 5) & 0x60);
port[1].data_w((data >> 1) & 0x60, (~data << 3) & 0x60);
/* Check for TH low-to-high transitions on both ports */
if ((!(io_reg[0x0F] & 0x80) && (data & 0x80)) ||
(!(io_reg[0x0F] & 0x20) && (data & 0x20)))
{
/* Latch new HVC */
hvc_latch = hctab[cycles % MCYCLES_PER_LINE] | 0x10000;
}
/* Japanese model specific */
if (region_code == REGION_JAPAN_NTSC)
{
/* Reading TH & TR pins always return 0 when set as output */
data &= 0x0F;
}
/* Update I/O Control register */
io_reg[0x0F] = data;
}
else
{
/* Memory Control register */
io_reg[0x0E] = data;
/* Switch cartridge & BIOS ROM */
sms_cart_switch(~data);
}
}
unsigned int io_z80_read(unsigned int offset)
{
/* Read port A & port B input data */
unsigned int data = (port[0].data_r()) | (port[1].data_r() << 8);
/* I/O control register value */
unsigned int ctrl = io_reg[0x0F];
/* I/O ports */
if (offset)
{
/*
Bit Function
--------------
D7 : Port B TH pin input
D6 : Port A TH pin input
D5 : CONT input (0 on Mega Drive hardware, 1 otherwise)
D4 : RESET button (1: default, 0: pressed, only on Master System hardware)
D3 : Port B TR pin input
D2 : Port B TL pin input
D1 : Port B Right pin input
D0 : Port B Left pin input
*/
data = ((data >> 10) & 0x0F) | (data & 0x40) | ((data >> 7) & 0x80) | io_reg[0x0D];
/* clear !RESET input */
io_reg[0x0D] |= IO_RESET_HI;
/* Adjust port B TH state if configured as output */
if (!(ctrl & 0x08))
{
data &= ~0x80;
data |= (ctrl & 0x80);
}
/* Adjust port A TH state if configured as output */
if (!(ctrl & 0x02))
{
data &= ~0x40;
data |= ((ctrl & 0x20) << 1);
}
/* Adjust port B TR state if configured as output */
if (!(ctrl & 0x04))
{
data &= ~0x08;
data |= ((ctrl & 0x40) >> 3);
}
}
else
{
/*
Bit Function
--------------
D7 : Port B Down pin input
D6 : Port B Up pin input
D5 : Port A TR pin input
D4 : Port A TL pin input
D3 : Port A Right pin input
D2 : Port A Left pin input
D1 : Port A Down pin input
D0 : Port A Up pin input
*/
data = (data & 0x3F) | ((data >> 2) & 0xC0);
/* Adjust port A TR state if configured as output */
if (!(ctrl & 0x01))
{
data &= ~0x20;
data |= ((ctrl & 0x10) << 1);
}
}
return data;
}
/*****************************************************************************
* Game Gear communication ports access *
* *
*****************************************************************************/
void io_gg_write(unsigned int offset, unsigned int data)
{
switch (offset)
{
case 1: /* Parallel data register */
io_reg[1] = data;
return;
case 2: /* Data direction register and NMI enable */
io_reg[2] = data;
return;
case 3: /* Transmit data buffer */
io_reg[3] = data;
return;
case 5: /* Serial control (bits 0-2 are read-only) */
io_reg[5] = data & 0xF8;
return;
case 6: /* PSG Stereo output control */
io_reg[6] = data;
psg_config(Z80.cycles, config.psg_preamp, data);
return;
default: /* Read-only */
return;
}
}
unsigned int io_gg_read(unsigned int offset)
{
switch (offset)
{
case 0: /* Mode Register */
return (io_reg[0] & ~(input.pad[0] & INPUT_START));
case 1: /* Parallel data register (not connected) */
return ((io_reg[1] & ~(io_reg[2] & 0x7F)) | (io_reg[2] & 0x7F));
case 2: /* Data direction register and NMI enable */
return io_reg[2];
case 3: /* Transmit data buffer */
return io_reg[3];
case 4: /* Receive data buffer */
return io_reg[4];
case 5: /* Serial control */
return io_reg[5];
default: /* Write-Only */
return 0xFF;
}
}
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